Various apparatus for an animal experiment have been planned, produced, and used. As a weight measuring apparatus, a balance has historically used in the animal experiment to measure weight of an animal. During measurement of the weight of the animal, measurement data of the animal changes constantly due to action of the animal, a measurement value (a displayed value) cannot be obtained stably, so that a balance for the animal experiment is adjusted to remove a bias placement error as long as possible so as to obtain the same measurement value wherever the animal stays. This adjustment is generally conducted by adjusting height of a Roberval mechanism, or a data processing. For example, a balance disclosed in Patent Literature 1 is widened its stable width for stopping or allowing its data loading of the measurement value by judging a state of data in activity or stability when the measurement data is averaged, thus, a data processing of the balance is stronger than a general data processing against vibration.
Meanwhile, in view of an animal protection and reduction of costs regarding the animal experiment, in a recent animal experiment, an experiment for observing the animal behavior due to influence of a mental illness and a genetic element is conducted instead of a typical method such as a direct method including a dissection. In this observation, it is important that how accurately the animal behavior or action can be measured and evaluated. For this, an image analyzing method by shooting with a CCD camera for a long stretch of time is conducted to analyze a moving distance per unit time, a movement of animal limbs at a constant position, moving area, or a destination point of the animal (refer to Patent Literature 2).